I checked out a Paul Lam DVD from the library and copied it to practice from way back when I first started my Taijiquan journey. Before I'd even found my first teacher.
It's very weird to see him without glasses or silk pajamas!
As far as I know/remember, and I could be wrong, his practice is 100% solo forms/"health", so his speaking to the working of forces, despite his reknowned mastery, has to be purely theoretical.
I'd love to be wrong, does he have any push hands videos? I just ask because I believe you need four hands to understand taijiquan.